Don’t mind me, I tend to overcomplicate things sometimes. Your friend was right, it’s not rocket science but I find if you take the time to understand the fundamentals of what makes certain things act the way they do, it will help you know what to do if you want to recreate a certain characteristic or put you in the right direction when you want to try something a little different. It helps to make things a little more predictable. I'm talking more about engineering here rather than the art of plug building. Plug building is an art and I don't presume to know what makes the best the best, but understanding some physics can't hurt when trying to figure things out.
Different wood grains and densities through the wood will change each plug. The CB/CG Separation in the plug from the top to bottom is what will cause an object to find it's static roll position. The CB will always float to a position directly above the CG in the water. The hooks of a plug will help force it into the orientation you are looking for most of the time. I was trying to avoid talking in 3D because it gets hard to visualize sometimes.
As far as a weight at the CG or CB goes, I’d determine it’s placement relative to the CG. Just an easier reference point because it’s easier to find. A plug should have it’s most unstable or “liveliest” behavior if the CB and CG are located in the same place in the center. Adding weight at different locations on the plug should effectively dampen some of the motion by requiring more force to get the plug to wiggle. Putting the weight further toward the bottom, or the belly, should help to dampen the roll of a plug at slow speeds. In the case of a metal lip plug this force is generated by water flowing by the lip creating an unstable flow at the nose. Back and forth, like a flag in the wind. The faster it goes, the quicker the flow goes to one side, followed by the force of drag on the side of the plug over coming this force on the nose, and the plug is pushed back the other way. Back and forth, back and forth… For instance, adding weight to the tail of a plug would be likely to slow the action of the plug and require it to be moving faster through the water in order to get it wiggling. Just a guess. A larger separation from the lip and the CG would need more speed to generate more force to get things rolling.
Like I said before, I’m basing my thoughts on physics and I’m probably missing about a thousand variables. It’s probably more effective to try something out and see what happens, maybe take notes, rather than to try to plan what’s going to happen from the start.
I’m surprised one of the professional plug builders here hasn’t chimed in yet to shut me up.
